Chitosan-Graphene Oxide Hydrogels with Embedded Magnetic Iron Oxide Nanoparticles for Dye Removal

We report a facile design and synthesis of magnetic iron oxide (IO) incorporated chitosan-graphene oxide (CSGO) hydrogel nanocomposites (CSGOIO) by employing in situ mineralization of iron ions in a hydrogel matrix. The mechanism of their formation was investigated by various physical methods, viz., FTIR, XRD, VSM, TGA, SEM, TEM, and BET. This approach was shown to have a direct impact on the morphological features and the structural order of the nanocomposites. The potential of the prepared nanocomposites for effective removal of a cationic dye, methylene blue (MB), from aqueous solution was investigated by performing a series of batch adsorption experiments, in line with the effect of adsorbent dosage, initial dye concentration, contact time, pH, ionic strength, and temperature. The adsorption was fairly influenced by the pH and ionic strength of the medium, indicating an electrostatic interaction between the adsorbent and MB molecules. The kinetics of adsorption followed a pseudo-second-order model, and equilibrium capacity was described by the Freundlich adsorption model. Interestingly, the nanocomposites exhibited a fast removal performance with a rate constant of 0.06 g mg^–1 min^–1. The hydrogel nanocomposites were found to possess an excellent adsorptive property after four successive cycles at different pH of the solution, thus providing a cost-effective material for dye removal applications. Therefore, this material, enabling dye removal in a wide variety of solution conditions, offered a promising platform for sustainable development of water purification technology.